analysis on composition and pattern of agricultural non ... · analysis on composition and pattern...
TRANSCRIPT
Analysis on composition and pattern of agricultural non-point source pollution in
Liaohe River Basin, China
Qingchun Wen, xin Chen *, Yi Shi, Jian Ma, Key Laboratory of Pollution Ecology and Environmental
Engineering Institute of Applied Ecology, Chinese Academy of
Sciences Shenyang, China
[email protected], [email protected], [email protected], [email protected]
Wen Qingchun Liaoning Environmental Monitoring Center
Shenyang, China. [email protected]
* Corresponding author.
Qian Zhao Liaoning Province Shiyan High School
Shenyang, China [email protected]
Abstract—The composition and spatial pattern of agricultural non-point source (NPS) pollution was studied in Liaohe River basin which is representative of areas of intensive NPS pollution in Northeast China. Selecting COD and ammonia nitrogen as the major pollutants, the export coefficient method and GIS spatial analysis methods were utilized to analyze the component composition and spatial distribution characteristics of NPS pollution in Liao River basin. The results showed that farmland runoff was the most significant source for the agricultural NPS pollution in the study area. Over 60 percents of the pollution loading was distributed in the Liaohe River mainstream area, and the pollution intensities were stronger in Hunhe River downstream and Liaohe River stem downstream plain sub-basins in Central-Western Liaoning province than in Hunhe River upstream and Taizihe hilly sub-basins in eastern Liaoning province.
Keywords- agricultural non-point source pollution; loading; composition; pattern
I. INTRODUCTION The main NPS pollution in Liaohe River is agricultural
NPS pollution, and most NPS pollution happens in the middle Liaohe River basin within Liaoning province, according to NPS pollution investigation for grade A areas in national water resource comprehensive planning [1]. As the natural conditions and social economical conditions vary in the basin area, the composition and spatial distribution of pollution differ. It is necessary to carry out further study on agricultural NPS pollution in Liaohe River basin, especially on its compositions and spatial pattern.
The export coefficient model is an empirical model [2-4], and depends less on experiments and relevant information on erosion, pollutant migration and transformation. As a black box method, it can utilize the easily obtained information on land use status, fertilization, and population to estimate
precisely, to some extent, the output of basin pollution, avoiding the complexity from NPS pollution process. It is widely used as a feasible method for long-term study on NPS pollution on middle and large basins [5-10].
In this paper, the export coefficient method was utilized to estimate the agricultural NPS pollution loading of Liaohe river basin, and GIS spatial analysis methods were utilized to analyze the spatial distribution characteristics of the pollution loading. The pollutant source types studied included rural life, farmland runoff and livestock.
Figure 1. Location of the study area
II. MATERIALS AND METHODS
A. Study Area The Liaohe River mainstream is 512 Km long, running
through Liaoning province, China, and the basin area is 69,100 Km2. The terrain of the basin declines from northeast to southwest, with its northeastern part being hilly and its central and southern parts being flat. The basin belongs to a temperate monsoon climate, with the annual precipitation varying from 350mm to 1000mm, 65% of which occurs
Study Area
Liaoning Province
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2011 2nd International Conference on Environmental Science and Technology IPCBEE vol.6 (2011) © (2011) IACSIT Press, Singapore
between April and September each year. The basin occupies all or most of the areas of the municipal cities of Tieling, Shenyang, Fushun, Anshan, Liaoyang, Benxi, Yingkou and Panjin, and smaller parts of Fuxin and Jinzhou. The population over the basin is about 24 millions and the area is one of the most important industrial and agricultural production bases in China.
B. Methods The formula for agricultural NPS pollution from Export
Coefficient method is
L = ( )[ ]∑=
n
iIiAiEi
1
,
where L represents the nutrition loss, Ei represents the export coefficient of nutrition source i which is the nutrition delivery ratio for each type of pollution source (e.g. farmland, livestock or population), Ai represents the area of land use type i, quantity of livestock type i or population number, and Ii represents nutrition production of unit pollution source type i, i.e. pollution source intensity coefficient or pollutant generating coefficient.
We obtained the relevant data of 2007 on population, livestock and farmland of every district or county in the study area from Liaoning Statistical Yearbook of 2008 [11]. COD and ammonia nitrogen were selected as the main pollutants. By referring to relevant literatures and taking into account the natural and economical conditions of the river basin, we determined the export coefficients and pollutant generating coefficients of COD and ammonia nitrogen generated from rural life, livestock and farmland runoffs respectively.
We analyzed the NPS pollutant composition in the study area by calculating the contribution of main pollutants from different pollution source, which were determined through calculating annual COD and ammonia nitrogen export loadings from rural life, livestock and farmland runoff. The basin is divided into six sub-basins according to its natural characteristics which are Liaohe River stem upstream, Liaohe River stem downstream, Hunhe River upstream, Hunhe River downstream, Taizihe sub-basin and Daliaohe sub-basin. We calculated the pollutant loading and loading intensity for each of them and analyzed the agricultural NPS pollution spatial variability of basin in the GIS spatial analysis model.
III. RESULTS AND DISCUSSION
A. Determination of main pollutant export coefficients for agricultural NPS pollution in Liaohe River Basin
1 ) The export coefficients of pollutants from rural life The rural life pollutant generating coefficients were
determined as 16.4 gram per person per day for COD and 4.0 gram per person per day for ammonia nitrogen, based on Technical Outline for Preparation of “National Drinking Water Source Protection Plan" [12]. There are no sewage treatment facilities in the rural areas, thus the export coefficient was determined as 1 (Table 1).
TABLE I. THE EXPORT COEFFICIENTS AND POLLUTANT GENERATING COEFFICIENTS OF RURAL LIFE
export coefficient
pollutant generating coefficients
COD(g/p·d)a NH3-N(g/p·d)
1 16.4 4 a. Gram per person per day
2 ) The export coefficients of pollutants from farmland The farmland pollutant generating coefficients were
determined based on Technical Outline for Preparation of “National Drinking Water Source Protection Plan" [12], and modified according to farmland gradient, soil type, precipitation and fertilization level (see Table 2). The export coefficient for the NPS pollution in Liaohe River basin was determined as 0.58, which is the smallest experiment value in Hao’s work in the same area (see Table 3) [1].
TABLE II. MODIFIED POLLUTANT GENERATING COEFFICIENTS OF FARMLAND RUNOFF
Modifying factors Modified coefficients
Gradient <25° 25° >25°
1.0-1.2 1.2 1.2-1.5
soil type loam Sand Clay
1 1.0-0.8 0.8-0.6
Precipitation <400mm/yr 400-800mm/yr >800mm/yr
0.6-1.0 1.0-1.2 1.2-1.5
fertilization <25kg 25-35 kg >35kg
0.8-1.0 1.0-1.2 1.2-1.5
TABLE III. THE EXPORT COEFFICIENTS AND POLLUTANT GENERATING COEFFICIENTS OF FARMLAND RUNOFF
export coefficient pollutant generating coefficients
COD(kg/ha·yr) NH3-N(kg/ha·yr)
0.58 150 30 a. Kilogram per hectare per year
3) The export coefficients of pollutants from livestock As there is almost no sewage treatment facility in the
study area, the pollutant generating coefficients of livestock was estimated as those of scattered livestock. The local farmers take the livestock emissions as manure, therefore the pollutant export was calculated as 12% of the emissions generated, according to Technical Outline for Preparation of “National Drinking Water Source Protection Plan" [12]. The pollutant generating coefficients for pigs, cattle, and sheep were determined according to GB18596-2001 Discharge standard of pollutants for livestock and poultry breeding and Practical Handbook of Fertilizer (see Table 4) [13-14].
TABLE IV. THE EXPORT COEFFICIENTS AND POLLUTANT GENERATING COEFFICIENTS OF LIVESTOCK
Livestock export pollutant generating coefficients
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type c
pig
cattle
sheep
B. Analysis oAgricultur
1 ) CompoCOD load
area was 321,farmland runolife contributesignificant cothan the ruralthe main agricThe farmlandmainstream, aTaizihe sub-bbasin’s pollutthat of rural li
Figure 2. The
Ammoniapollutants wawas contributand rural lifpollution sourCOD.
oefficient C
0.12
0.12
0.12
on compositionral NPS polluosition of pollding generated,986 tons in 20off contributeed 42.8%. Th
ontribution anl life. The agricultural NPS pd runoff occuand less than
basins. Except tion contributiife (see Fig 2)
composition of C
a nitrogen gs 66,997 tons ted by farmlafe. As shownrces for ammo
COD(g/i·d)a
50
500
16.7 a. G
n and pattern tion in the stulution source d by agricultur007 (seeTableed 57.2%, thehe farmland rnd the livestocicultural farmpollution factoupied over 60
50% in HunHunhe River
ion by livesto.
COD loading sour
generated by(see Table 5)
and runoffs ann in Fig 3, onia nitrogen
NH3-N(g/i
10
100
3.3Gram per individual live
characteristiudy area
ral NPS in the
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ock was great
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y agricultural), among whicnd 45% by livthe compositis similar to t
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cs of
e study hich the nd rural he most d more
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l NPS ch 55% vestock tion of that for
reagpefaNPco
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Figure 3. The c
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gricultural popeople there is armland runoffPS pollution c
ontributed less2 ) Spatial pa
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mainstream, wiontributing 44gricultural NPhich occupiedas also ser
omparatively lub-basin (see T
TABLE V.
Sub-basin
Stem upstreamStem
downstreamHunhe River
upstreamHunhe River downstream
Taizihe
Daliaohe
Basin total
The pollutiohe basin’s areaensity and indading intensit
nd could be uauses of agricu
The COD loreatly in the rear. The CODiver downstreee Fig.4). T
ntensities in thccording to thiver downstrehich are loca
gricultural conad greatest aelonged to levre located in hrable farmlanensity are lownd belonged toaliaohe sub-baom eastern h
composition of Nb
area is locatee arable farmpulation densit
relatively lowff contributedcomposition, s. attern characpatial distribu
was distributeith its upstream.2% and 19.4%
PS pollution. Nd 16.0%. The rious in Hulittle in HunhTable 5).
THE DISTRIBUTIRIVE
COD(t/yr.
142468
62500
15399
38508
51543
11570
321988
on loading of ta on one handdustrial structuty represents thsed to furtherulture NPS poloading intensirange of 0.01D loading inteam and smaThe agricult
he study area wheir determineam and Liaated in centranditions and dagriculture N
vel I. Hunhe Rhilly eastern
nd per capitawer, had the sm
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NH3-N loading sobasin
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) NH3-N(
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3235
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2467
6699
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Liaoning proa and agricu
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astern China apita and a snsumption levbe the reason art in Liaohe Rstock and rura
ollution loadinS pollution oin Liaohe R
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ream and Dali
LUTANTS IN LIAO
t/yr.) perce
64 44.2
73 19.4
5 4.8%
8 12.0
10 16.0
7 3.6%
97 100.0
et is influencebasin’s populher. The poll
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ed into three lsee Fig.5). HStem downstrprovince with ultural populan intensities
m and Taizihe bvince, where ultural popul
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V1-182
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Figure 4. The
Figure 5. The
The analycharacteristicsbasin showedto the pollutioand rural life distributed msub-basins. TRive mainstreplain sub-basTaizihe hilly s
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IV. ysis on the coms of agricultur
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ACKNO
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CONCLUSION
mposition andral NPS pollud runoff contrthe study are
ess. The agricuhe River mainintensities weRiver downst
ak in Hunhe
OWLEDGMENT
n and Guan ing the pape
ween those of
y distribution in L
y levels in Liaoh
N d spatial distr
ution in Liaoheributed the moea, and the livultural NPS ponstream and Tere strong intream and DaRiver upstrea
T Yongchun fo
er. This stud
f level I
Liaohe
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ribution e River ost part vestock ollution Taizihe Liaohe aliaohe
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or their dy was
finfo
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